This application claims the priority of Korean Patent Application No. 2003-42789, filed on Jun. 27, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a de-interlacing method and apparatus, which transform an interlaced format video into a progressive format video, and a video decoder and a reproducing apparatus using the same.
2. Description of the Related Art
In general, a video signal is realized in an interlaced format or a progressive format. An interlaced format video signal includes a plurality of fields. A progressive format video signal includes a plurality of frames. One frame is made by merging two fields so that lines of one of the two fields are arranged between lines of the other. The interlaced format video signal can supply higher video quality with less amount of data than the progressive format video signal. However, since the interlaced format video signal requires two fields to display one picture, signal processing for reproduction is relatively complicated.
In case of a reproducing apparatus, such as a TV, which can handle the progressive format video signal, if the interlaced format video signal is input, the interlaced format video signal must be handled after the interlaced format is transformed into the progressive format. The format conversion is called de-interlacing or interlaced-to-progressive conversion (IPC).
The de-interlacing process includes an interpolation process for transforming fields included in the interlaced format video signal to frames. The interpolation is largely divided into a temporal interpolation using an average of two temporally adjacent pixels and a spatial interpolation using an average of two spatially adjacent pixels. The de-interlacing by the spatial interpolation is called two dimensional de-interlacing. The de-interlacing using both of the temporal interpolation and the spatial interpolation according to circumstances considering motion of the video signal is called three dimensional de-interlacing.
In the three dimensional de-interlacing, a conventional interpolation process is as follows. When a current field is interpolated, after a difference value between pixels of a previous field and a next field corresponding to a pixel to be interpolated is obtained, if the difference value is less than a predetermined threshold value, the temporal interpolation is performed by determining that a small motion exists, and if the difference value is more than the predetermined threshold value, the spatial interpolation is performed by determining that a large motion exists.
However, even though the difference value between the pixels of the previous field and the next field corresponding to the pixel to be interpolated is less than the predetermined threshold value, an object or a background quite different from objects or backgrounds of the previous field and the next field can exist in the current field, like, for example, when a hand is quickly moved up and down. Nevertheless, if the temporal interpolation is performed based on the difference value between the pixels of the previous field and the next field being less than the predetermined threshold value, an actual value of the pixel to be interpolated becomes noise and cannot be associated with adjacent pixel values.